Migrate database from Sql Server 2008 to MySql,error

[jjc king]

Hi all, i want migrate a database from Sql Server 2008 to MySql using a the tool MySql Migration Toolkit but when the tool is establishing the database connection i receive this error :

Connecting to source database and retrieve schemata names.
Initializing JDBC driver ...
Driver class MS SQL JDBC Driver
Opening connection ...
Connection jdbc:jtds:sqlserver://localhost:1433/Northwind;user=sa;password=;charset=utf-8;domain=
The list of schema names could not be retrieved (error: 0).
ReverseEngineeringMssql.getSchemata :Login failed for user 'sa'.
Details:
net.sourceforge.jtds.jdbc.SQLDiagnostic.addDiagnostic(SQLDiagnostic.java:365)
net.sourceforge.jtds.jdbc.TdsCore.tdsErrorToken(TdsCore.java:2781)
net.sourceforge.jtds.jdbc.TdsCore.nextToken(TdsCore.java:2224)
net.sourceforge.jtds.jdbc.TdsCore.login(TdsCore.java:599)
net.sourceforge.jtds.jdbc.ConnectionJDBC2.<init>(ConnectionJDBC2.java:331)
net.sourceforge.jtds.jdbc.ConnectionJDBC3.<init>(ConnectionJDBC3.java:50)
net.sourceforge.jtds.jdbc.Driver.connect(Driver.java:178)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
com.mysql.grt.modules.ReverseEngineeringGeneric.establishConnection(ReverseEngineeringGeneric.java:141)
com.mysql.grt.modules.ReverseEngineeringMssql.getSchemata(ReverseEngineeringMssql.java:99)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
com.mysql.grt.Grt.callModuleFunction(Unknown Source)
in SQL Server i have not user and password to connect to the database(Window Authentication) so in the Connection Parameter of SQL i insert in the Username field = "sa" and leaving blank the field password.

Do you have any idea why i receive this Error and how work out this issue?

Thanks so much for your attention.

Cheers :)